Improvement in psychosocial outcomes in chronic pain patients receiving intrathecal morphine infusions.

BACKGROUND

When conventional multimodal analgesic therapy is unsuccessful, more aggressive analgesic treatments are required for patients with intractable chronic pain. Despite extensive clinical experience with implanted morphine pumps, there is still controversy regarding the psychosocial effects of this invasive analgesic therapy. In this prospective study, we evaluated the impact of intrathecal (IT) morphine infusions on pain perception and psychosocial functionality. A secondary objective of this pilot study was to assess the effect of IT morphine infusion on the patient's level of functional activity.

METHODS

Thirty patients with chronic nonmalignant pain that failed to respond to multimodal analgesic regimens were evaluated using the McGill Pain Questionnaire before and at 3-, 12-, and 24-mo intervals after implantation of an IT morphine infusion pump. At each clinic visit, the patient's level of pain was assessed using an 11-point visual analog scale, with 0 = no pain and 10 = worse pain imaginable. The mean initial morphine infusion rate was 0.23 +/- 0.14 mg/day (with a range from 0.09 to 0.75 mg/day) and was subsequently adjusted to maintain their pain score at a value <50% of the initial value. Adverse side effects and complications, as well as activity levels, were recorded at each clinic visit.

RESULTS

Both evaluative and affective components of the pain assessment demonstrated a significant improvement over the 24-mo study period. The evaluative component of the McGill Pain Questionnaire improved 66%, the affective component 59%, and the sensory component 32%. The average morphine infusion rate increased to 0.44 +/- 0.29, 0.66 +/- 0.39, and 0.80 +/- 0.45 mg/day at the 3-, 12-, and 24-mo follow-up intervals (P < 0.05). The reduced level of chronic pain leads to improved social, work, and family relationships and quality of life. Among 13 patients of working age, 12 returned to work full time, and among 17 retired patients, 14 had a reduced need for assistance.

CONCLUSIONS

IT infusion of morphine using an implantable pump was helpful in improving psychosocial function in patients with intractable pain that had failed to respond to standard multimodal analgesic therapy.